An NC device is conventionally configured to compare the entirety of position feedback data from an amplifier with the entirety of program command data or parameter references of a machining program. The NC device compares only shapes of respective pieces of the program command data with the feedback data without performing comparison of data as time-series data (see, for example, Patent Literature 1 mentioned below).
The NC device is also configured to store the position of a machine at a time when a specific command in a machining program is issued, and stores an issuance timing of the specific command in the machining program and a machine position only of that time associated with each other (see, for example, Patent Literature 2 mentioned below).
The NC device is also configured to place specific marks or commands on interested parts in a machining program, and outputs only data of the parts in which the specific marks or commands are described (see, for example, Patent Literature 3 mentioned below).